`WritableSignal.update()`

Computes a writable signal's next value from its current value.

Since Angular 16+ Spec ↗

Syntax

update(updateFn: (current: T) => T): void

Parameters

Name	Type	Required	Description
`updateFn`	`(current: T) => T`	No	Function receiving the current value and returning the next one.

Returns

void — Nothing; consumers are notified if the value changed.

Examples

import { signal } from '@angular/core';

const count = signal(0);
count.update((n) => n + 1);

const list = signal<string[]>([]);
list.update((arr) => [...arr, 'item']);

Notes

Prefer update() over set() when the next value depends on the current one; it avoids reading the signal separately. Return a new reference for objects and arrays so equality detects the change and consumers re-run.